(CNN) -- Farmers are on their way to tend their crops when a missile slams into their midst, thrusting shrapnel in all directions.
A CIA drone, flying so high that the farmers can't see it, has killed most of them. None of them were militants.
It's a common scenario, a United Nations human rights researcher said Friday in a statement on drone strikes in Pakistan's tribal region of North Waziristan.
Special Rapporteur Ben Emmerson just returned from the region, where he listened to residents talk about terrifying encounters with one of America's weapons in the war on terror.
"Adult males carrying out ordinary daily tasks were frequently the victims of such strikes," the statement from the U.N. office for human rights said.
Some Pashtun men dress the same as Taliban members from the same region, hence the drone operators mistake them for terror targets, the statement said. It is also customary for Pashtun men to carry a weapon, making them virtually indistinguishable from militants to an outsider.
The United States has 8,000 drones, unmanned planes and helicopters flown by a remote control. They are outfitted with a video camera to help the operator spot targets and often armed with weapons used to neutralize them.
President Barack Obama has told CNN that a target must meet "very tight and very strict standards."
CIA director John Brennan has said that only in "exceedingly rare" cases have civilians been "accidentally injured, or worse, killed in these strikes."
Reports back the U.N. conclusion
Reports by independent groups corroborate Emmerson's account, concluding that drones mistakenly target and kill a significant number of civilians.
The New America Foundation estimates that in Pakistan, drones have killed between 1,953 and 3,279 people since 2004 - and that between 18% and 23% of them were not militants. The nonmilitant casualty rate was down to about 10% in 2012, the group says.
A study by the Bureau of Investigative Journalism estimates that since 2004, Pakistan has had 365 drone strikes that have killed between 2,536 and 3,577 people -- including 411 to 884 civilians.
The study concludes that the strikes have killed far more people than the United States has acknowledged, and traumatized many more innocent people.
That trauma is destroying a way of life, Emmerson said. "The Pashtun tribes of the ... area have suffered enormously under the drone campaign."
And tribal law prescribes revenge for the killing of a tribe member, which serves to radicalize more young men against the United States, he said.
Pakistan considers the strikes counterproductive, illegal and a violation of its sovereignty.